1. Field of the Invention
This invention relates generally to an apparatus and a method for inserting discrete articles into surgical cartridges, and more particularly to an improved device and method for inserting springs into surgical stapling cartridges.
2. Description of the Related Art
In the field of microsurgery, a surgical instrument having a cutting blade traverses a specific path through tissue. One feature of the surgical instrument is a single-use cartridge that is a holder for surgical staples. The cartridge is an elongated plastic body with a longitudinal channel that serves as a guide for a surgical blade. The cartridge has rows of small staples on opposite sides of the channel, and these rows are aligned parallel to the guide channel. Drivers are inserted in apertures (also called “pockets”) aligned with the rows in order to push the staples out of the cartridge and through the adjacent tissue. Before the blade has made its cut, each side of the incision is stapled together by displacing the drivers relative to the cartridge. This displacement forces the staples against an anvil on the opposing side of the surgical instrument as the cartridge and the anvil deflects the points of the staples into a clasping position.
There may be as many as fifty or more very small staples on each side of a two-inch incision. Each staple can be driven into the tissue to close the incision by the correspondingly small drivers. The task of inserting the drivers into the cartridge is labor-intensive due to the small size of the drivers.
It is known in the prior art to insert drivers mechanically into surgical stapling cartridges, as shown in U.S. Pat. No. 5,836,147 to Schnipke, U.S. Pat. No. 5,653,928 to Schnipke, U.S. Pat. No. 6,158,205 to Schnipke et al., and U.S. Pat. No. 7,207,168 to Doepker et al., all of which are incorporated herein by reference. Workers manually position the cartridges, and the holders that contain the drivers relative to the machine, in the machines disclosed in these patents, and then actuate the machine to insert the tiny drivers into the pockets in the cartridges. After a fraction of the total number of drivers is inserted by one machine, the cartridge is then manually transported to the next machine, which inserts another fraction of the drivers. In U.S. Pat. No. 6,729,119 to Schnipke et al., which is incorporated herein by reference, a robotic loader is described for use in filling the cartridges discussed herein with the use of fewer workers than the prior art.
During the surgical procedure in which the surgical cartridges described above are used, the surgeon displaces two “sleds” longitudinally by manually depressing a trigger or otherwise actuating the surgical device that holds the cartridge. During this actuation, the sleds of the cartridge drive the drivers out of their home position, thereby driving the staples into the tissue, and a knife is displaced to make the incision. It is important that the knife make the incision either after, or while, the staples are driven into the tissue. In order to prevent a surgeon from mistakenly making another incision with a cartridge that has already driven its staples, a small, V-shaped lockout spring is mounted in the cartridge at the end near the sleds. This V-shaped spring has two legs that expand outwardly to occupy a portion of the space that the sleds occupy in their home positions. When the legs are in the expanded position, the spring acts as a “barb” that prevents the surgical device in which the cartridge is mounted from making a second incision without a new cartridge. This spring feature is obviously important to the safe operation of the cartridge, and therefore, the surgical instrument in which the cartridges are inserted.
It is known to insert springs into the cartridges by mechanical means, such as by pre-compressing the springs and forcing them mechanically downwardly into the slot between the opposing sleds. There is, however, no way known to Applicants to rapidly and conveniently test springs prior to insertion to determine if they have sufficient spring force to work properly as the required safety feature.
Therefore, there is a need for a machine for testing and loading springs into surgical cartridges.